A gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of a working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a shaft connected, e.g., to a generator to produce electricity. The combustion gases then exit the gas turbine via the exhaust section.
The turbine section includes a plurality of turbine rotor blades, which extract kinetic energy from the combustion gases flowing therethrough. Each of the turbine rotor blades include a pressure side wall and a suction side wall coupled together at a leading edge and a trailing edge. The pressure side and the suction side walls each exhibit a vibratory response motion (e.g., for a specific natural frequency) when excited by unsteady combustion gas pressures or other transient conditions in the turbine section. In certain instances, the turbine rotor blade may be sufficiently stiff to couple the vibratory responses of the pressure side and the suction side walls. This increases the natural frequency of blade and may coincide with the excitation frequency of unsteady gas pressures. In such instances, pressure side and the suction side walls may vibrate in phase with each other, which may be undesirable.